Notice the use of the MAYBE_ moniker: it's possible that the name of the test is an identifier in the testing code, e.g., the name of the test is the same name as the method being tested in the test.

FAILS_ and FLAKY_ are no longer used:

Previously FAILS_ and FLAKY_ prefixes were used to continue running tests and collecting results. Due to build bot slowdowns and false failures for developers we no longer do so. This was discussed in the Feb 2012 Disabling Flaky Tests thread.

FAILS_ and FLAKY_ are ignored by the builders and not run at all. To collect data for potential flaky tests, just enable them as normal, the builder will automatically retry any tests 3 tests, so the flakiness shouldn't cause any tree closures (but the flakiness dashboard will still be told of those flakes).